Apparatus for measuring distances with a measuring element operating on an optical basis

Abstract

Distances are measured by a measuring element operating on an optical basis by sensing light reflections caused by the bending in unison of at least two parallel light conductors. The measuring element has two parallel photoconductors of different lengths extending from a sensor inlet of a carrier, e.g., in the form of a sheath. The effective length of each conductor is determined by a respective mirror at the effective conductor end. Through the introduction of light into the shorter photoconductor and by the bending of the light conductors, light is coupled over to the second photoconductor. The extent of bending is measured by ascertaining the intensity and travel time of the reflections from both conductors. A reflection only from the shorter light conductor indicates that there is no bending or deflection of the two light conductors and hence no distance is being measured.

What I claim is: 
     
       1. An apparatus for measuring distance, comprising at least two parallel light conductors, support means for holding said at least two light conductors in a fixed parallel position relative to each other, said support means permitting a bending or deflection of said two light conductors in unison for coupling of light from one light conductor into the other light conductor as a function of said bending or deflection, a reflecting mirror at an effective first end of each light conductor so that each light conductor has a different optically effective length, whereby one conductor is shorter than the other, source means for introducing light into said shorter light conductor at a second end opposite said first reflecting end, light sensor means positioned to receive reflected light from each light conductor at said second end for providing respective light signals representing a measure of said bending or deflection of said light conductors, said measure in turn corresponding to the distance to be measured, and wherein a reflection only from said shorter light conductor indicates that no deflection or bending is taking place. 
     
     
       2. The apparatus of claim 1, wherein said light conductors comprise more than two light conductors arranged in parallel to each other for an improved sensitivity and precision. 
     
     
       3. The apparatus of claim 1, wherein said light conductors comprise a central core light conductor and at least one tubular light conductor arranged concentrically to said core light conductor, said core light conductor being shorter than said tubular light conductor. 
     
     
       4. The apparatus of claim 1, further comprising optical time multiplexing means including said light source for introducing light into the shortest light conductor and said light sensor means for sensing reflected light from each of said light conductors, said time multiplexing means further including a central processing unit for evaluating received light signals with regard to the light intensity and different propagation times of said light signals. 
     
     
       5. The apparatus of claim 4, comprising a plurality of sensors each comprising said at least two light conductors, and optical data bus means connecting said sensors to said time multiplexing means.